Clean the pork fillet and pierce the centre with a skewer to obtain a pocket. Drain the mozzarella and place on absorbent paper to remove as much water as possible. Mash the mozzarella with the chopped olives and tomatoes. Season the mixture with fresh ground black pepper and lemon zest. Press the mozzarella filling into the pork fillet, securing the open end with cocktail sticks. Seal the pork in a frying pan with the butter, a glug of olive oil, garlic cloves and the springs of rosemary. De-glaze the pan with the wine and turn down the heat to reduce the sauce. Add in the stock, cover the pan with a lid and cook for further 15 min. To Make the crushed potatoes, simmer the washed potatoes in boiling water until they are cooked through. Whilst still warm, carefully peel the potatoes and crush slightly with a fork. Mix in the olive oil, chopped garlic, chopped chilli, parsley and season with salt & pepper. Serve the stuffed pork fillet with the olive oil crushed potatoes. Suggested accompanying wine: DELICATA Medina Syrah D.O.K. Superior Malta